1. Field of the Invention
The present invention relates to a polycrystalline structure film often utilized for a magnetic recording layer of a magnetic recording medium such as a hard disk (HD), for example, and to a method of making the same.
2. Description of the Prior Art
A continuous layer of a polycrystalline structure is often utilized for a magnetic recording layer in the technical field of magnetic recording media. The continuous layer of the polycrystalline structure includes minute Co alloy crystalline grains formed on the surface of the base layer based on the epitaxy. The continuous layer of the polycrystalline structure allows Cr atoms to diffuse along grain boundaries between the adjacent Co alloy crystalline grains. The Cr atoms form non-magnetic walls between the adjacent Co alloy crystalline grains, so that magnetic interaction is reliably prevented between the adjacent Co alloy crystalline grains. Magnetic domains are established in the individual crystalline grains. As conventionally known, fine Co alloy crystalline grains serve to reliably reduce noise in a read signal for magnetic information.
For example, an ordered alloy such as Fe50Pt50 (atom %) exhibits a remarkably larger crystalline magnetic anisotropy energy as compared with Co alloy. The crystalline magnetic anisotropy energy of the ordered alloy often reaches over 1×106 J/m3, for example. A larger crystalline magnetic anisotropy energy serves to maintain magnetization within a fine crystalline grain. On the other hand, a smaller crystalline magnetic anisotropy energy causes loss of magnetization within a fine crystalline grain due to thermal agitation. Utilization of an ordered alloy is desired in place of Co alloy so as to realize fine crystalline grains. However, a continuous layer of a polycrystalline structure made of an ordered alloy cannot enjoy the aforementioned diffusion of non-magnetic atoms along the grains boundaries. Magnetic interaction should reliably be cut off between the adjacent crystalline grains made of an ordered alloy.